1 //===-- ClangExpressionVariable.h -------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CLANGEXPRESSIONVARIABLE_H
10 #define LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CLANGEXPRESSIONVARIABLE_H
11 
12 #include <csignal>
13 #include <cstdint>
14 #include <cstring>
15 
16 #include <map>
17 #include <string>
18 #include <vector>
19 
20 #include "llvm/Support/Casting.h"
21 
22 #include "lldb/Core/Value.h"
23 #include "lldb/Expression/ExpressionVariable.h"
24 #include "lldb/Symbol/TaggedASTType.h"
25 #include "lldb/Utility/ConstString.h"
26 #include "lldb/lldb-public.h"
27 
28 namespace llvm {
29 class Value;
30 }
31 
32 namespace clang {
33 class NamedDecl;
34 }
35 
36 namespace lldb_private {
37 
38 class ValueObjectConstResult;
39 
40 /// \class ClangExpressionVariable ClangExpressionVariable.h
41 /// "lldb/Expression/ClangExpressionVariable.h" Encapsulates one variable for
42 /// the expression parser.
43 ///
44 /// The expression parser uses variables in three different contexts:
45 ///
46 /// First, it stores persistent variables along with the process for use in
47 /// expressions.  These persistent variables contain their own data and are
48 /// typed.
49 ///
50 /// Second, in an interpreted expression, it stores the local variables for
51 /// the expression along with the expression.  These variables contain their
52 /// own data and are typed.
53 ///
54 /// Third, in a JIT-compiled expression, it stores the variables that the
55 /// expression needs to have materialized and dematerialized at each
56 /// execution.  These do not contain their own data but are named and typed.
57 ///
58 /// This class supports all of these use cases using simple type polymorphism,
59 /// and provides necessary support methods.  Its interface is RTTI-neutral.
60 class ClangExpressionVariable
61     : public llvm::RTTIExtends<ClangExpressionVariable, ExpressionVariable> {
62 public:
63   // LLVM RTTI support
64   static char ID;
65 
66   ClangExpressionVariable(ExecutionContextScope *exe_scope,
67                           lldb::ByteOrder byte_order, uint32_t addr_byte_size);
68 
69   ClangExpressionVariable(ExecutionContextScope *exe_scope, Value &value,
70                           ConstString name, uint16_t flags = EVNone);
71 
72   ClangExpressionVariable(const lldb::ValueObjectSP &valobj_sp);
73 
74   ClangExpressionVariable(ExecutionContextScope *exe_scope,
75                           ConstString name,
76                           const TypeFromUser &user_type,
77                           lldb::ByteOrder byte_order, uint32_t addr_byte_size);
78 
79   /// Utility functions for dealing with ExpressionVariableLists in Clang-
80   /// specific ways
81 
82   /// Finds a variable by NamedDecl in the list.
83   ///
84   /// \return
85   ///     The variable requested, or NULL if that variable is not in the list.
86   static ClangExpressionVariable *
87   FindVariableInList(ExpressionVariableList &list, const clang::NamedDecl *decl,
88                      uint64_t parser_id) {
89     lldb::ExpressionVariableSP var_sp;
90     for (size_t index = 0, size = list.GetSize(); index < size; ++index) {
91       var_sp = list.GetVariableAtIndex(index);
92 
93       if (ClangExpressionVariable *clang_var =
94               llvm::dyn_cast<ClangExpressionVariable>(var_sp.get())) {
95         ClangExpressionVariable::ParserVars *parser_vars =
96             clang_var->GetParserVars(parser_id);
97 
98         if (parser_vars && parser_vars->m_named_decl == decl)
99           return clang_var;
100       }
101     }
102     return nullptr;
103   }
104 
105   /// If the variable contains its own data, make a Value point at it. If \a
106   /// exe_ctx in not NULL, the value will be resolved in with that execution
107   /// context.
108   ///
109   /// \param[in] value
110   ///     The value to point at the data.
111   ///
112   /// \param[in] exe_ctx
113   ///     The execution context to use to resolve \a value.
114   ///
115   /// \return
116   ///     True on success; false otherwise (in particular, if this variable
117   ///     does not contain its own data).
118   bool PointValueAtData(Value &value, ExecutionContext *exe_ctx);
119 
120   /// The following values should not live beyond parsing
121   class ParserVars {
122   public:
123     ParserVars() = default;
124 
125     const clang::NamedDecl *m_named_decl =
126         nullptr; ///< The Decl corresponding to this variable
127     llvm::Value *m_llvm_value =
128         nullptr; ///< The IR value corresponding to this variable;
129                  /// usually a GlobalValue
130     lldb_private::Value
131         m_lldb_value;            ///< The value found in LLDB for this variable
132     lldb::VariableSP m_lldb_var; ///< The original variable for this variable
133     const lldb_private::Symbol *m_lldb_sym =
134         nullptr; ///< The original symbol for this
135                  /// variable, if it was a symbol
136 
137     /// Callback that provides a ValueObject for the
138     /// specified frame. Used by the materializer for
139     /// re-fetching ValueObjects when materializing
140     /// ivars.
141     ValueObjectProviderTy m_lldb_valobj_provider;
142   };
143 
144 private:
145   typedef std::map<uint64_t, ParserVars> ParserVarMap;
146   ParserVarMap m_parser_vars;
147 
148 public:
149   /// Make this variable usable by the parser by allocating space for parser-
150   /// specific variables
151   void EnableParserVars(uint64_t parser_id) {
152     m_parser_vars.insert(std::make_pair(parser_id, ParserVars()));
153   }
154 
155   /// Deallocate parser-specific variables
156   void DisableParserVars(uint64_t parser_id) { m_parser_vars.erase(parser_id); }
157 
158   /// Access parser-specific variables
159   ParserVars *GetParserVars(uint64_t parser_id) {
160     ParserVarMap::iterator i = m_parser_vars.find(parser_id);
161 
162     if (i == m_parser_vars.end())
163       return nullptr;
164     else
165       return &i->second;
166   }
167 
168   /// The following values are valid if the variable is used by JIT code
169   struct JITVars {
170     JITVars() = default;
171 
172     lldb::offset_t m_alignment =
173         0;             ///< The required alignment of the variable, in bytes
174     size_t m_size = 0; ///< The space required for the variable, in bytes
175     lldb::offset_t m_offset =
176         0; ///< The offset of the variable in the struct, in bytes
177   };
178 
179 private:
180   typedef std::map<uint64_t, JITVars> JITVarMap;
181   JITVarMap m_jit_vars;
182 
183 public:
184   /// Make this variable usable for materializing for the JIT by allocating
185   /// space for JIT-specific variables
186   void EnableJITVars(uint64_t parser_id) {
187     m_jit_vars.insert(std::make_pair(parser_id, JITVars()));
188   }
189 
190   /// Deallocate JIT-specific variables
191   void DisableJITVars(uint64_t parser_id) { m_jit_vars.erase(parser_id); }
192 
193   JITVars *GetJITVars(uint64_t parser_id) {
194     JITVarMap::iterator i = m_jit_vars.find(parser_id);
195 
196     if (i == m_jit_vars.end())
197       return nullptr;
198     else
199       return &i->second;
200   }
201 
202   TypeFromUser GetTypeFromUser();
203 
204   /// Members
205   ClangExpressionVariable(const ClangExpressionVariable &) = delete;
206   const ClangExpressionVariable &
207   operator=(const ClangExpressionVariable &) = delete;
208 };
209 
210 } // namespace lldb_private
211 
212 #endif // LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CLANGEXPRESSIONVARIABLE_H
213